Steam power system



Sept. 4, 1962 P. PRoFos 3,052,223

STEAM POWER SYSTEM Filed March 10, 1959 4 Sheets-Sheet 1 INVENTOR. Po u I P r0 f o s BY WQMQTQIQD ATTORNEYS P. PROFOS 3,052,223

Sept. 4, 1962 STEAM POWER SYSTEM 4 SheetsSheet 2 Filed March 10, 1959 FIG. 2

' INVENTOR Poul Profos ATTORNEYS P 1962 P. PROFOS STEAM POWER SYSTEM 4 Sheets-Sheet 5 Filed March 10, 1959 Vi al .071%?! IlO INVENTOR Poul Profos ATTORNEYS P. PROFOS STEAM POWER SYSTEM Sept. 4, 1962 4 Sheets-Sheet 4 Filed March 10, 1959 FIG. 4

FIG.6

BY FWQLWM United States Patent 3,052,223 STEAM POWER SYSTEM Paul Profos, Winterthur, Switzerland, assignor to Sulzer Freres, Societe Anonyme, Winterthur, Switzerland, a Swiss company Filed Mar. 10, 1959, Ser. No. 798,418 Claims priority, application Switzerland Mar. 11, 1958 10 Claims. (Cl. 122479) The present invention relates to steam power systems including a forced-circulation boiler and an engine (e.g. a turbine) having at least two stages, in which the steam is sent through a superheater in the boiler in the course of its passage from the first to the second stage of the engine for reheat.

According to the invention, the boiler comprises two separate firing spaces, preferably having separate exhaust stacks. The water tube system, or at least the portion thereof which serves for completion of evaporation and initial superheating, is divided into two parts, one in each of the firing spaces or stacks. According to a further feature of the invention, the tube system for the final superheating is disposed in one of the firing spaces (or in the stack thereof), whereas the tube system of the interstage superheating, i.e. for the superheating imposed on the steam in its passage from one engine stage to the next, is disposed in the other firing space or in its stack. Moreover, a Water separator is provided in each half of the boiler between the evaporation or conversion zone and the initial superheating zone. Moreover, the half of the tube system disposed in the same firing space as the inter-stage superheater or reheater is provided with a control device which limits introduction of the working substance into the initial superheater of that half when the fluid content thereof exceeds a predetermined limit, to which the control device is sensitive.

The invention will now be further described with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a steam power system according to the invention;

FIG. 2 is a schematic diagram of apparatus for operation of the valve 30 in FIG. 1 controlling the passage of steam into the initial superheater 17 according to its degree of dryness;

FIG. 3 is a schematic diagram of another apparatus useable in place of that in FIG. 2;

FIG. 4 is a diagram of still another apparatus useable in place of the apparatus of FIG. 2;

FIG. 5 is a fragmentary schematic diagram showing a modification of the boiler construction of FIG. 2; and

-F IG. 6 is a sectional view taken on the line 6-6 of FIG. 5.

As illustrated in FIG. 1 the steam power system of the invention comprises a forced-circulation boiler generally indicated at 1, a two-stage turbine 2, a condenser 3, and a feed water supply tank 4. A load in the form of an alternator 33 is shown coupled to the turbine.

The boiler includes separate firing spaces 6 and 7 separated by a wall 5. Separate combustion gas stacks Sand 9 connect with the firing spaces 6 and 7 respectively and are likewise separated by the wall 5. The firing spaces are fired by separate burners indicated at 10 and 11. The gases of combustion pass through the stacks 8 and 9 into a common exhaust 12.

The water tube system for vaporization and initial superheating is divided into two parts. The feed water inlet conduit 13 divides at a T-junction 14 into separate conduits which lead to the vaporizing tube systems 15 and 16, onein each of spaces 6 and 7. Tube systems 15 and 16 in turn connect with initial superheaters 17 and 18. At a junction 19 the initial superheaters 17 and 18 are reunited for connection to a common final superice heater 20. It can thus be seen that each vaporizing tube system and series-connected initial superheater is separate and isolated from the other intermediate its ends.

In its passage through the boiler the Working substance is thus divided at 14 into two halves, each half being converted into steam and subjected to initial superheating in a separate tube system. The two halves of the working substance are then reunited at 19 and superheated together to the final temperature.

Between each of the Vaporizers 15 and 16 and the initial superheaters 17 and 18 there is provided a Water separator drum, these being indicated at reference characters 21 and 22. The water separated is drawn off at the conduits 23 and 24. Valves 25 and 26 are disposed in the conduits 23 and 24 for control of the amount of Water drawn oil at these separators. The valves 25 and 26 operate according to the humidity content of the steam passing through separators 21 and 22, as measured by devices 27 and 28. These devices will be further described presently in connection with FIGS. 2, 3 and 4.

The final superheater 20 is disposed in the stack 9. In the other stack 8 there is disposed an inter-stage superheater or reheater 29 for restoring to a higher temperature the exhaust steam from the high pressure stage of the engine 2 before its application to the low pressure stage thereof.

The tube systems 15 and 17, which together with the inter-stage superheater 29 are disposed in the firing space 6 with its appurtenant stack 8, are 'further provided with a valve 30 controlling flow of the working substance from the steaming tube system 15 into the initial superheater 17 according to the quantity of water in the separator 21. When the fluid content of the working substance passing into the superheater 17 exceeds a permissible level, the valve 30 limits or shuts off this flow. The water or fluid in the separator 21 provides a suflicient measure of this content. Control of valve 30 by device 27 will be further described below by reference to FIGS. 2, 3 and 4.

The valve 30 so controlled materially facilitates firing up of the whole power system from a cold start. Forced circulation boilers are provided only for installations of large power capacity having plural firing chambers. Such installations must be very carefully fired up in order to avoid the introduction of water into the turbine or other engine on the one hand, and on the other hand to avoid burning out of parts of the tube system. The boiler shown in FIG. 1 is put into operation by firing first only the burner 11 for the spaces 7 and 9. During this initial firing, valve 31 is held closed and the working substance, e.g. Water, passes only through the tube system 16, 18 where it is heated to higher and higher temperatures as the firing progresses. When this heating has progressed to such a point that the working substance is available as slightly superheated steam, it is passed through the high pressure stage of the turbine 2 (not yet placed in rotation) and thence through the reheater 29 and the low pressure stage of the turbine. The turbine is drained and progressively raised in temperature by the working substance toward its intended operating temperature.

At about this stage of the run-up process the burner 10 is set into operation and water is admitted to the tube system 15, 17, at least to the extent required to prevent damage thereto. Care is to be taken of course, that in this process no water is drawn at the junction 19 from the initial superheater 17 into the already superheated steam passing from initial superheater 18 to final superheater 20, since such water might damage the turbine 2 now coming into rotation. The valve 30 and its control device 27 precisely prevent flow of the work: ing substance from the tube system 15 into the system 17 so long as its fluid content exceeds a permissible level.

The valve 30 permits passage of the working substance into tubes 17 only when the working substance contains no'more fluid than can be definitively vaporized in the initial superheater 17, so that no water damage is to be feared to the turbine 2.

The device 27 for control of valve 30 can berconstructed to measure the level of the water in the separator 21, for example by a weighing operation, with suitable elastic support for the separator drum or for a sampling vessel connected thereto by flexible tubings to have therein the same fluid level as the separator drum. From the level so measured, as an approximate measure of the humidity of the steam emerging from the vaporizer '15, the device 27 adjusts the setting of the valve 30 for passage of the working substance from the separator 21 into the superheater 17. It is also possible of course to control the valve 30 according to a direct humidity measurement on the steam passing at 19 into the final superheater 20. Alternatively the valve 30 may be ad'- justed by the operation of a control means responsive to the rate at which water is extracted by the separator 21. p

The invention is of advantage for firing up of the power system even if the two firing spaces are not then mally isolated from each other, as by a masonry partition such as the wall of FIG. 1, but are instead separated only by tube walls, separating the heat radia: tion and gas streaming process in the two firing spaces. Such a construction is shown in FIGS. 5 and 6. The two stacks can be united at the upper end thereof into a common stack 12 as shown in FIG. 1, where economizers, and also superheater and/ or vaporizer units may be disposed. Conversely, of course, such elements of the system may also be disposed within the separate stacks 8 and 9, close to the exhaust end thereof. The economizer can also serve an initial steaming function so that the separate tube systems 15 and 16 are fed with a mixture of water and steam. It is also possible to dispose part of the vaporizing tubes in the exhaust stack or stacks, and to dispose portions of the superheater elements in the firing spaces.

\ FIGURE 2 shows schematically one form of apparatus fulfilling the function of device 27 in FIG. 1 for control and operation of the valve 30 according to the humidity content of the steam, FIG. 2 showing in addition elements 15, 17, 21, 23, 25 and the valve 30 itself from FIG. 1. In the device 27 thus illustrated in FIG. 2 a diaphragm 50 is disposed in an enlargement in the steam tube between valve 30 and superheater 17. Diaphragm 50 effects of course only a partial obstruction of the line. The pressures existing on opposite sides of the diaphragm 50 are communicated by tubes 5-1 to the two halves of an aneroid cell 52. A slidably mounted rod 53 connects to the diaphragm of the cell, and its motion is communicated by suitable means such as the linkage 34 to a slidably mounted rod 54. Rod 54 is aflixed at one end to a cam 55 and at the other to a piston 56 movable in a cylinder 57, which is hydraulically connected by a conduit 58 with that one of the conduits 51 exposed to the high pressure side of diaphragm 50. A further slidably mounted rod 59 rides at one end on cam 55 and the other end of this rod is connected to a spring 60. A further rod 61, slidably mounted collinearly with rod 59, receives at one end the stress of spring 60 and is coupled at its other end by a linkage 35 to a slidable rod 62. Rod 62 is coupled at one end to a cam 63 and at the other to a piston 64, movable in a cylinder 65 which is connected by a conduit 66 with the steam tube of the vaporizer 15 at the end thereof leading to the separator 21.

A slidably mounted rod 67 rides at one end of the cam 63 and its other end is connected to one end of a spring 68. The other end of the spring 68 is connected by a rod 68 to the three-piston movable body 36 of a valve 69 which controls the application of hydraulic fluid,

under pressure from a source not shown, to the opposite sides of a servo piston 74 which controls valve 30. Valve body 36 is also subjected by a rod 37 to the force exerted on the diaphragm of an aneroid cell 70, the upper and lower sides of which are connected by conduits 71 to the pressures existing in the bled-off line 23 from the separator 21, above and below a measur ing diaphragm 72 which may be similar to the diaphragm 50.

A float 75 is provided in the separator for operation of the valve 25 via a linkage 76. A measuring diaphragm is provided in the feed water line to vaporizer 15. Conduits 81 communicate the pressures on either side of this diaphragm to an aneroid cell 82. A rod 83 coupled at one end to the diaphragm of this cell is coupled at the other end to a cam 85 pivoted at 84. A follower rod 86 is slidably mounted between cam 85 and a spring 87, and a rod 88 is coupled between the spring 87 and a lever 89 the other end of which connects to the rod 61.

The difierence between the rate of flow of water into the separator, measured at diaphragm 80, and the rate of flow of steam beyond the valve 30, measured at diaphragm 50, is a measure of the humidity content of the steam passing into the superheater 17. The difference is equal to the water drawn off at the conduit 23. The difference between the two measurements at diaphragms 50 and 80 is applied to the cam 63 and thence to the valve 69, which is also influenced in its setting by the rate at which water is taken off from the separator. When the bleed-01f through valve 25 is too small, i.e. when the difference between the water fed into the separator and the steam taken off through valve 30 is too small, the valve body 36 will move upwardly. Hydraulic fluid is then admitted into the right hand conduit 73 against the piston 74 to close the valve 30, thus preventing the introduction of the excessively wet steam into the superheater *17. Valve 30 opens again when the difference between water input to the separator and steam output therefrom is great enough so that the steam entering superheater 17 exhibits the proper low degree of humidity.

FIGURE 3 shows another form of apparatus for operation of the valve 30 as a function of the steam humidity. In this embodiment there is employed a multi-element thermostat of which however only a single element is shown for simplicity of the drawing. In this embodiment the vaporizer 15 is divided into a plurality of parallelconnected channels 15', 15", etc. At the steam end of each of these channels there is provided a thermometer comprising a rod of material having a very low coeflicient of thermal expansion. These rods are coupled each at one end to one of the vaporizer tubes 15, 15" and at the other end to one end of a lever 38 having a fixed pivot. The other end of each lever 38 is coupled via a rod 39 to a separate control piston 101. A conduit 102 leads from the cylinder 39' in which piston 101 works through a check valve 103 to a header 104 into which all conduits 102 terminate. A conduit 105 leads from the header 104 to a cylinder 106 containing a piston 107. The rod 108 of this piston is coupled to a cam 109 and is further coupled by a linkage 40 to a slidably mounted rod 110 which is linked to a piston 111. Piston 111 works in a cylinder 41 connected through a conduit 112 to the header 42 leading from the steam ends of Vaporizers 15', 15" etc. to the separator 21. A follower rod 113 is arranged to ride at one end on the cam 109 and has its other end connected to a spring 114. A rod 68', connected at one end of the body 36 of a valve 115, like the valve 69 of FIG. 2, connects at its other end to spring 114. The other end of valve body 36 is connected to one end of a spring 116, the far end of which is fixed in position. Two conduits 117 lead from the valve to opposite sides of a piston 118 which operates the Valve 30 via a rod 119;

The separator 21 is provided with a floater 75 as in the embodiment of FIG. 2 for operation of the valve 25.

In the embodiment of FIG. 3 the humidity of the steam is measured as a function of its pressure and temperature. Consequently, the temperature is measured at the output end of the vaporizing coils 15, 15" etc. and the pressure is measured there also, by means of conduit 112 and piston 111. The results of the two measurements are applied via cam to the control of valve 115. Valve 30 is then held via the servo piston 118 in closed or open position according as the steam is too damp or too dry.

FIG. 4 illustrates an alternative construction already referred to in which valve 30 is controlled in accordance with the weight of water in the separator. In this embodiment however it is not the separator itself but a smaller vessel 13!? which is elastically suspended for weighing of its contents. The vessel 130 is connected via two flexible conduits 131 with the separator 21 and is so positioned that the liquid level in the vessel 130 is the same as in the separator. A rod 132 is coupled to the bottom of the vessel 130 for operation of the valve 25 in such a fashion that when the vessel 130 is moved downwardly, the valve 25 is opened, and vice versa. Two stops 133 and 133 are provided on the side of the vessel 130. The end of a lever 134 pivoted on a fixed pivot at 42 extends to a position between the stops. The other end of this lever connects through a rod 135 with the operating lever 43 of the valve 30. When the fluid, i.e. liquid level in the vessel 130 exceeds a predetermined height, the weight of the liquid therein forces vessel 1% down and the stop 133' rotates the lever 134 clockwise, tending to close valve 30 and to open valve 25, by operation of a lever 132 connected between valve 25 and vessel 130. When the liquid level in vessel 13% declines to a specified lower level the vessel will lift sufliciently so that stop 133 rotates lever 134 in the opposite sense, tending to open valve 30 and to close valve 25. Valve 30 is therefor adjusted only at two limiting values for the level in the separator and not continuously as is the case with valve 25.

While the invention has been described herein in terms of a number of presently preferred embodiments, the invention itself is set forth in the appended claims.

I claim:

1. A forced circulation steam generator of the oncethrough type for a two stage steam-consuming machine, said generator comprising two parallel connected combinations of a converter and an initial superheater in series therewith, said combinations being separate and isolated from each other intermediate their ends, separate firing means each firing one of said combinations, a final superheater fired by one of said firing means, said final superheater being input-connected to the outputs of both of said combinations and adapted to be output-connected to the high pressure stage of said machine, an interstage superheater fired by the other of said firing means, a separator between each of said converters and its series-connected initial superheater, and means controlling, in accordance with the fluid content of the working substance flowing through the separator between the converter and initial super-heater fired by the other of said firing means, the flow of working substance into the initial superheater fired by the other of said firing means, so that the flow of working substance to the initial superheater is increased as said fluid content decreases, and vice versa.

2. A forced circulation steam generator of the oncethrough type for a :two stage steam-consuming machine, said generator comprising two firing spaces, separate and isolated converter and a series-connected initial superheater in each of said spaces, 'a final superheater in one of said spaces input-connected to the outputs of both of said initial superheaters and adapted to be output-connected to the high pressure stage of said machine, an intersta-ge superheater in the other of said spaces, a separator between each of said convertersand its series-connected initial superheater, and means to increase the flow of work- 6 ing substance into the initial superheater in said other space directly as the difference between the rates of flow of working substance through the converter and initial superheater in the other of said spaces is increased, and vice versa.

3. A forced circulation steam generator of the oncethrough type for 'a two stage steam-consuming machine, said generator including 'lIWlO firing spaces, separate and isolated converter and a series-connected initial superheater in each of said spaces, a final superheater in one of said spaces input-connected to the outputs of both of said initial superheaters and adapted to be output-connected to the high pressure stage of said machine, an interstage super-heater in the other of said spaces, a separator between each :of said converters and its series-connected initial superheater, and means controliing the flow of working substance into the initial superheate-r in said other space, said control means comprising a valve insented between said last-named superheater and its seriesconnected converter, separate means to measure the rates of flow of working substance through said last-named superheater and converter, and means to increase the opening of said valve directly with the difference between said rates of flow and vice versa.

4. In a forced-circulation boiler of the once through type having two firing spaces, separate and isolated steam conversion and series-connected initial superheating means in each of said spaces connected in parallel between a feed water supply and a final superheater disposed one of said spaces, a reheater disposed in the other of said spaces, and a separator between each of said conversion and initial superheating means, means to regulate the passage of steam into the initial superheating means in the other of said spaces, said regulating means comprising means to measure the wetness of the steam passing into the separator between the conversion and initial superheating means in said other space, a valve at the input to the initial .superheater in said other space, and means controlled by said wetness measuring means to increase the opening in said valve inversely with said wetness, and vice versa.

5. In a forced-circulation boiler of the once-through type having two firing spaces, separate and isolated steam conversion and series-connected initial superheating means each of sad spaces connected in parallel between a feed Water supply and a final superheater in one of said spaces, a reheater disposed in the other of said spaces, and a separator between each of said conversion and initial superheating means, means to regulate the passage of steam into the initial superheater in the other of said spaces, said regulating means comprising means to generate signals representative of the temperature and pressure of the steam passing into the separator between the conversion and initial superheating means in said other space, a valve at the input of said last-named superheater, and servo mechanism responsive to said signals to increase the opening of said valve as said temperature increases and said pressure decreases, and vice versa.

6. In a forced-circulation boiler of the once-through type having two firing spaces, separate and isolated steam conversion and series-connected initial superheating means in each of said spaces connected in parallel between a feed water supply and a final superheater in one of said spaces, and a separator between each of said conversion and initial superheating means, means to regulate the passage of steam into the initial superheating means in the other of said spaces, said regulating means comprising a valve contnollin-g the passage of steam through said last-named superheater means, means to measure the liquid level in the separator associated with said last-named superheatin-g means, and means to increase the opening of said valve when said liquid level decreases to a predetermined extent, and vice versa.

7. In a forced-circulation boiler of the once-through type having two firing spaces, separate and isolated steam 7 conversion and and series-connected initial superheating means in each of said spaces connected in parallel between a feed water supply and a final super heater in one of saidspaces, a separator between each of said conversion and initial superheating means, and a drain valve in each ot said separators, means to regulate the passage of steam into the initial superheating means in the other of said spaces, said regulating means comprising a valve controlling the passage of steam through said lastnamed superheating means, means to measure the liquid level in the separator associated with said last-named superheating means, and means to vary in opposite senses the opening of said control valve and of the drain valve in said last-named separator in accordance with variations in said liquid level, so that the opening of said control valve is increased when the liquid level decreases to a predetermined extent.

8. A forced circulation steam generator of the oncethrough type for a two stage steam-consuming machine, said generator comprising two parallel-connected combinations of a converter and an initial superheater in series therewith, said combinations being separate and isolated from each other intermediate their ends, separate firing means each firing one of said combinations, a final superheater fired by one of said firing means, said final superheater being input-connected to the outputs of both of said combinations and adapted to be output-connected to the high pressure stage of said machine, an interstage superheater fired by the other of said firing means, a separator between each of said converters and its series-connected initial super-heater, and means to vary the flow of working substance into the superheater fired by the other of said firing means, said varying means comprising a valve at the input to said last-named initial superheater, separate means to measure the temperature and pressure of the working substance at the outlet of the converter fired by the other of said firing means, and means to increase the opening of said valve as said temper-ature increases and as said pressure decreases.

9. A forced circulation steam generator of the oncethrough-type for a two stage steam-consuming machine, said generator comprising two parallel-connected combinations of a converter and an initial superheater in series-therewith, said combinations being separate and isolated from each other intermediate their ends, separate firing means each firing one of said combinations, a final superheater fired by one of said firing means, said final superheater being input-connected to the outputs of both of said combinations and adapted to be output-con nected to the high pressure stage of said machine, an interstage superheater fired by the other of said firing means,

a separator between each of said converters and its seriesconnected initial superheater, and means to vary the flow of working substance into the initial superheater fired by the other of said firing means, said varying means comprising a valve at the input to said last-named initial superheater, separate means to measure the temperature and pressure of the steam at the outlet of the converter fired by the other of said firing means, separate means to develop motions representative respectively of said measured temperature and pressure, and servomechanism responsive to said motions for increasing the opening of said valve as said temperature increases and as said pressure decreases.

10. A forced circulation steam generator of the oncethrough type for a two stage steam-consuming machine, said generator comprising two parallel-connected combinations of a converter and an initial superheater in series therewith, said combinations being separate and isolated from each other intermediate their ends, each of said conventers including a plurality of parallel-connected channels, said generator further comprising separate firing means each firing zone of said combinations, a final superheater fired by one of said firing means, said final superheater being input-connected to the outputs of both of said combinations and adapted to be output-connected to the high pressure stage of said machine, an interstage superheater fired by the other of said firing means, a separator between each of said converters and its seriesconnected initial superheater, and means to vary the flow of working substance into the initial superheater fired by the other of said firing means, said varying means comprisin g a valve at the input to said last-named initial superheater, separate means to measure the steam temperature in each of the channels of the converter fired by said other firing means, means to develop a motion representative of the highest of said temperatures, means to measure the steam pressure at the outlet end of the converter fired by the other of said firing means, means to develop a motion representative of said pressure, a cam coupled to said motions, and a servomechanism responsive to motion of said cam for increasing the opening of said valve as said temperature increases and as said pressure decreases.

References Cited in the file of this patent UNITED STATES PATENTS 2,081,948 

